Preparation Of Graphene-based Composite Materials And Its Application For Energy Storage

With the development of industrialization process of human society,the energy and environmental problems become increasingly severe.It is urgent to develop environmental friendly new energy to replace the fossil energy.Fuel cell and lithium ion battery are two kinds of energy storage devices possess excellent application prospect.Graphene due to it’s excellent physical and chemical properties,electrochemical properties,and unique thin and soft two-dimensional structure make itself popular used in the field of new energy.In addition,graphene has been used as supports of nanoparticles due to its large specific surface area.Direct alcohol fuel cell（DAFC）has attracted wide attention by the researchers due to its high energy density,environment friendly character.The traditional DAFC faced some serious problems,such as high cost and low stability of the catalyst.Therefore,the design of catalysts with low cost,high catalytic activity and high stability of the catalyst became a hot topic in the DAFC research.To solve above problems,the high catalytic activity and high stability of the Pd-based catalysts have been designed and prepared.In this paper,a two step method has been used to prepare Pd-Cu/RGO,the load of Pd nanoparticles was 10%.Using X-ray diffraction（XRD）,Transmission electron microscopy（TEM）,Inductive Coupled Plasma Emission Spectrometer（ICP）,X-ray photoelectron spectroscopy（XPS）and some other test methods to study the composition and morphology of nanoparticles.The electrochemical catalytic activity of composite was studied using cyclic voltammetry and chronoamperometry in alkaline environment.The experimental results showed that after the second step reaction the composite formed a core-shell like structure and its catalytic activity is significantly higher than the first step production.Also different ratios of Pd/C u have different catalytic activities.Lithium ion batteries have high energy density,long cycle life are have been widely used in various types of portable electronic devices.The capacity of current commercial anode materials of lithium ion battery is not high so limits the electrochemical properties of the battery.And electrode material is the vital factor to improve the performance of lithium ion battery,so design and preparation of high performance anode materials is a key factor to improve the performance of the battery.Based on graphene based materials,using hydrothermal method prepare the composite（CoWO₄/RGO）,and study its electrochemical performance act as the anode materials of lithium ion baterry.Because of graphene oxide has high electrical conductivity,make up for the metal salt weaknesses of poor electrical conductivity.Graphene layers structure also can improve the speed of electron and ions fluxion,so that can increase the lithium ion battery performance.XRD,TEM,EDS and other tests prove that the formation of CoWO₄ nanoparticles.The experimental results show that when the current density is 100 mAg-1,CoWO₄ / RGO has high specific capacity（1132.9 mAhg-1）.In ratio performance CoWO₄ / RGO composite material also showed more stable performance than CoWO₄ material.